Ice Storm and Heavy Snow in Texas, January 19 to 20, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LUBBOCK TX
554 AM CST FRI JAN 19 2007

.SHORT TERM...
FORECAST REMAINS ON TRACK FOR A MAJOR WINTER STORM TO AFFECT THE SOUTH
PLAINS WITH HEAVY SNOWFALL LIKELY FOR MUCH OF THE CWA.

6Z GUIDANCE HAD THE UPPER LOW AT H5 ANALYZED JUST SOUTHWEST OF SAN
DIEGO. WV IMAGERY SHOWS DEVELOPING BAROCLINIC LEAF STRUCTURE WITH
THE WARM CONVEYOR BELT AHEAD OF THE LOW/TROUGH TRANSPORTING A RICH
SUBTROPICAL MOISTURE PLUME NORTHEASTWARD INTO NEW MEXICO AND WEST
TEXAS. IR IMAGERY HAS SHOWN AN ENHANCEMENT/COOLING TREND TO CLOUD
FIELD ACROSS NM. MODEL GUIDANCE IS IN DECENT AGREEMENT DEPICTING THE UPPER
LOW MOVING TO A POSITION NEAR THE SRN AZ/NM BORDER BY SAT MORN.
THE NAM H5 TRACK REMAINS SLIGHTLY SLOWER THAN THE OTHER MODELS AND
IS PREFERRED WITH THIS PATTERN. THE NAM/GFS INDICATE LIFT IN THE I295-300K
LAYER SPREADING NORTHWARD FROM THE WESTERN PERMIAN BASIN TODAY.
REGIONAL RADARS ARE SHOWING INCREASING ECHO STRENGTH AND COVERAGE
ACROSS THE PERMIAN BASIN AND SE NM AND EXPECT THIS TREND TO CONTINUE
THROUGH THE MORNING HRS.

INITIAL BAND OF PRECIP IS ON THE DOORSTEP OF OUR SRN COUNTIES AT 5
AM CST. THE PRECIP WILL INITIALLY BE LIGHT AS SATURATION PROCEEDS
FROM THE MID-LVLS DOWN TO THE SFC. PRECIP TYPE IS A MAJOR CONCERN
FOR TODAY. 06Z KMAF SOUNDING SHOWED FAIRLY DEEP WARM NOSE AROUND 800MB. 5
TO 10 DEGREE DEW POINT DEPRESSIONS SHOULD PRODUCE STRONG EVAPORATIVE
COOLING THAT SHOULD BEGIN TO EAT AWAY AT THE WARM LAYER.
TEMPERATURES ARE FCST TO BE VERY CLOSE TO FREEZING FROM AROUND THE
700MB LEVEL TO THE SFC IN MOST LOCATIONS FOR MOST OF THE DAY AND
CONTINUING TONIGHT. ADDITIONALLY...FCST PROFILES FROM THE NAM
CONTINUE TO BE SLIGHTLY WARMER THAN THOSE OF THE GFS...AND INDICATE
WIDER COVERAGE OF SLEET AND FREEZING RAIN FROM THE SRN SPLNS THROUGH
THE ROLLING PLAINS. THIS WILL HAVE IMPLICATIONS FOR THE FCST OF SNOW
AND ICE ACCUMULATIONS. THE 6Z NAM RUN CONFINES SIGNIFICANT SNOWFALL
ACCUMULATION TO THE SW PANHANDLE AND FAR WEST SPLNS AND IS LIKELY
INCORRECT. OUR PREVIOUS FCSTS HAVE INDICATED THE SNOW/SLEET BOUNDARY TO
BE ROUGHLY FROM A BROWNFIELD TO LUBBOCK TO SILVERTON LINE...AND THIS
STILL APPEARS TO BE VALID. NORTH AND WEST OF THIS LINE SHOULD SEE
THE HEAVIEST SNOWFALL. HAVE ADJUSTED QPF AND SNOWFALL TOTALS DOWN
THROUGH THE DAYLIGHT HRS. STILL EXPECT FROM 1 TO 4 INCHES BEFORE 6PM
WITH LESSER AMOUNTS FARTHER EAST AND SOUTH. PRECIP SHOULD THEN
CONTINUE TO EXPAND AND INTENSIFY TONIGHT AS LIFT INCREASES. FCST
X-SECTIONS SHOW THE DOMINANT PRECIP TYPE TONIGHT SHOULD BE SNOW
WITH MODERATE LIFT AND DEEP-LAYER SATURATION IN THE DENDRITIC GROWTH
LAYER. SLEET MAY MIX IN AT TIMES ON THE CAPROCK AND HAVE ADDED AN
AREA OF FRZG RAIN ACROSS THE SRN ROLLING PLAINS IN THE GRIDS AND
DEPENDING ON THE ACTUAL TEMPS THEY COULD SEE SIGNIFICANT ICE
ACCUMULATIONS. SOME PERIODS OF HEAVY SNOWFALL WILL BE POSSIBLE
MAINLY NEAR THE NM BORDER BY EARLY SAT MORNING. INHERITED TYPE AND
CONFIGURATION WARNINGS ALSO LOOK GOOD.

SFC WINDS ARE EXPECTED TO REMAIN EASTERLY AND FAIRLY LIGHT THROUGH
THE PERIOD WITH LITTLE DIURNAL TEMPERATURE RANGE.

.LONG TERM...
WINTER STORM CONDITIONS WILL BE ONGOING ACROSS THE FA SATURDAY
MORNING. IN FACT...THE HIGHEST SNOW PROBABILITIES/RATES APPEAR TO
OCCUR DURING THE 06Z TO 21Z SAT TIMEFRAME. HIGH CONFIDENCE REMAINS
IN A MAJOR WINTER WEATHER EVENT OVER THE SOUTH PLAINS REGION. MINOR
DIFFERENCES IN MODEL SOLUTIONS REMAIN. THE GFS CONTINUES TO BE THE
MOST PERSISTENT/AGGRESSIVE WITH HIGH-END STORM CONDITIONS. THE WRF/
NMM HAS DISPLAYED FLUCTUATIONS IN PRECIP/THERMAL PROFILES...WITH
A BRIEF TREND TOWARD THE GFS OVERNIGHT. A GFS WEIGHTED COMPOSITE
OF BOTH SOLUTIONS IS CURRENTLY PREFERRED GIVEN OBSERVATIONS...AND
NATIONAL HPC/WWD GUIDANCE SUPPORTS THIS WITH HIGH PROBABILITIES OF
SIGNIFICANT ACCUMULATIONS.

INCREASINGLY DIFFLUENT MID LEVEL FLOW WILL SPREAD EAST OVER THE
PLAINS OF EASTERN NEW MEXICO AS THE UPPER LOW BEGINS TO QUICKLY
EJECT OVER THE SOUTHERN PORTIONS OF THAT STATE SATURDAY. IN ADVANCE
OF THIS FORCING...A STRONG WAA RESPONSE IS NOTED WITH ISENTROPIC
UPGLIDE MAXIMIZED WITHIN THE 290 TO 300K LAYER. FORECAST SOUNDINGS
DIFFER BY SOLUTION...BUT GENERALLY FEATURE HEAVY SNOW PROFILES
OVER THE WEST/NORTH FA...WITH PERIODS OF SLEET/FREEZING RAIN OVER
THE SOUTHEASTERN ZONES WHERE WAA RESULTS IN A LARGE ISOTHERMAL
LAYER BETWEEN 0 AND 3 DEGREES C CENTERED ON THE 700MB LEVEL. AN
ABNORMALLY DEFINED FETCH OF SUBTROPICAL MOISTURE CONTINUES TO
STREAM NORTHWARD IN ADVANCE OF THE UPPER LOW. THIS YIELDS VERY
DEEP/MOIST PROFILES WITH A POTENTIAL FOR HIGHLY EFFICIENT PRECIP
PRODUCTION. ALTHOUGH P-TYPE FORECAST IS VERY COMPLEX...RATES
SHOULD BE VERY HIGH. WILL MAINTAIN THE PREVIOUSLY FORECASTED ST
ACCUMULATIONS OF 6 TO 12+ INCHES IN THE HEAVY SNOW WARNING AREA.
WILL ADJUST WEATHER GRIDS TO ACCOUNT FOR AN INCREASED LIKELIHOOD
OF FREEZING RAIN/ICE OVER THE SOUTHERN ROLLING PLAINS.

THE THREAT FOR ADDITIONAL ACCUMULATING WINTRY PRECIP WILL DIMINISH
LATE BY EARLY SATURDAY EVENING AS DOWNGLIDE AND ASSOCIATED DRY SLOT
SPREADS EAST OVER THE REGION. EXPECT BREEZY SOUTHWESTERLY WINDS IN
THE WAKE OF THE PASSING TROUGH SATURDAY NIGHT/EARLY SUNDAY. A COLD
FRONT WILL PUSH SOUTH ACROSS THE AREA LATE SUNDAY...JUST AS THE NEXT
UPPER TROUGH DIGS INTO THE DESERT SOUTHWEST. THIS SYSTEM IS PROGGED
TO EJECT EASTWARD OVER THE U.S./MEXICO BORDER REGION AND TRANS PECOS
MONDAY AND TUESDAY. ANOTHER THREAT OF ACCUMULATING SNOWFALL WILL
RESULT OVER PARTS OF THE WESTERN/SOUTHERN SOUTH PLAINS.

&&

.PRELIMINARY POINT TEMPS/POPS...
FRIONA        28  19  30  21  31 /  90 100 100  40  10
TULIA         29  20  28  20  31 /  80 100 100  50  10
PLAINVIEW     29  21  28  22  32 /  90 100 100  40  10
LEVELLAND     29  22  29  23  33 /  90 100 100  20  10
LUBBOCK       29  23  30  23  34 /  90 100 100  30  10
BROWNFIELD    29  22  30  24  34 / 100 100 100  20  10
CHILDRESS     33  25  31  24  34 /  70  90 100  50  10
SPUR          31  23  32  25  35 /  80 100 100  40  10
ASPERMONT     33  25  32  26  36 /  80 100  90  30  10

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST SATURDAY FOR THE FOLLOWING
ZONES: TXZ025-026-031-032-036>038-041>044.

HEAVY SNOW WARNING UNTIL 6 PM CST SATURDAY FOR THE FOLLOWING
ZONES: TXZ021>024-027>030-033>035-039-040.

&&

33/20

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LUBBOCK TX
618 AM CST FRI JAN 19 2007

TXZ021>044-201230-
PARMER-CASTRO-SWISHER-BRISCOE-HALL-CHILDRESS-BAILEY-LAMB-HALE-
FLOYD-MOTLEY-COTTLE-COCHRAN-HOCKLEY-LUBBOCK-CROSBY-DICKENS-KING-
YOAKUM-TERRY-LYNN-GARZA-KENT-STONEWALL-
618 AM CST FRI JAN 19 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE EXTREME SOUTHERN TEXAS
PANHANDLE...SOUTH PLAINS AND ROLLING PLAINS.

.DAY ONE...TODAY AND TONIGHT

A POTENTIALLY DANGEROUS WINTER STORM WILL BEGIN TO IMPACT THE
SOUTH PLAINS REGION TODAY. SNOW...POSSIBLY MIXED WITH SLEET AND
PERIODS OF FREEZING RAIN...WILL OVERSPREAD THE REGION THROUGH THE
DAY. THE THREAT FOR HEAVY SNOW WITH SIGNIFICANT ACCUMULATIONS WILL
INCREASE TONIGHT. A HEAVY SNOW WARNING IS IN EFFECT FOR AREAS ON
THE CAPROCK...A WINTER STORM WARNING IS IN EFFECT OVER THE ROLLING PLAINS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

MAJOR WINTER STORM CONDITIONS WILL PERSIST THROUGH SATURDAY.
SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED OVER THE WESTERN AND
NORTHERN OUTLOOK AREA...WITH ISOLATED STORM TOTALS IN EXCESS OF
ONE FOOT POSSIBLE. SIGNIFICANT SNOW...SLEET...AND ICE
ACCUMULATIONS ARE POSSIBLE OVER THE EASTERN AND SOUTHERN PARTS OF
THE OUTLOOK AREA. HEAVY SNOW AND WINTER STORM WARNINGS ARE IN EFFECT.

ANOTHER STORM SYSTEM IS EXPECTED TO AFFECT THE REGION MONDAY INTO
TUESDAY WITH THE THREAT FOR ADDITIONAL ACCUMULATING SNOWFALL.

.SPOTTER INFORMATION STATEMENT...

PREPARATIONS FOR A MAJOR WINTER STORM SHOULD BE COMPLETED.
EMERGENCY OFFICIALS AND LAW ENFORCEMENT AGENCIES ARE URGED TO
RELAY REPORTS OF WINTRY PRECIPITATION AND ITS IMPACTS TO THE
NATIONAL WEATHER SERVICE OFFICE IN LUBBOCK TEXAS.